Endotracheal tubes are used to provide reliable ventilation and oxygenation to patients with compromised breathing pathways. If a patient is not ventilating or suffers an airway blockage for four minutes and no oxygen can reach the patient, he or she will likely suffer brain damage; if the blockage continues for eight minutes, the patient will likely suffer brain death through either hypoxic brain damage or cardiopulmonary arrest. In cases where the patient's airway is blocked, the time it takes to establish and secure a reliable airway and restore oxygen flow to the patient's lungs is critical.
Endotracheal tube systems are inserted in a patient's airway to provide a conduit to secure a reliable breathing pattern through a secure pathway. In this manner, after either an attempted or successful direct laryngoscopy, the system is most commonly inserted into the patient's airway through the mouth, past the epiglottis and larynx, and into the trachea. In some cases a stylet is first positioned within the endotracheal tube to provide rigidity or stiffness to the semiflexible endotracheal tube which may assist with proper placement of the endotracheal tube within the trachea and not in the esophagus. If a stylet is used, the medical professional inserts an endotracheal tube over the stylet to add rigidity to the endotracheal tube and facilitate the endotracheal tube placement to the desired location. The stylet is then removed and a sealing cuff is inflated leaving a hollow tracheal tube to provide a secure, patent and unobstructed airway. The cuff is a potential space on the proximal end of the endotracheal tube that seals the airway making the endotracheal tube the only lumen for gas exchange for the patient's pulmonary system. This will also prevent oral or gastric contents from entering the patient's lungs.
This procedure requires many steps and is often met with various obstacles. For instance, the endotracheal tube may be incorrectly positioned within the esophagus. If incorrectly positioned within the esophagus, the patient will not receive sufficient, if any, airflow to the lungs. Therefore, a need exists to provide a system and method for reliably determining if the tracheal tube is correctly placed within the trachea thereby providing an unobstructed pathway to the patient's lungs.
One method of determining proper placement of the endotracheal tube, and therefore allowing for proper ventilation of the patient, is to measure the concentration of carbon dioxide within the exhaled gas. Typically, exhaled carbon dioxide gas from a patient's lungs is between 30 mmHg and 40 mmHg (but can range at times between 20 mmHg and 80 mmHg or higher). If proper endotracheal tube placement and ventilation is achieved, the patient's exhaled gas has a measurable concentration of carbon dioxide. If the endotracheal tube is improperly placed within the esophagus there should be no sustained or significant concentration of carbon dioxide in the exhaled gas. Therefore, there exists a need to reliably and quickly measure the concentration of carbon dioxide within the exhaled gas to ensure proper placement of the tracheal tube and proper ventilation.